Answer:
x = 11.5
Explanation:
Formula
a^2 = b^2 + c^2 - 2*b*c * cos(A) Substitute givens in formula
Givens
- b = 31
- c = 26
- A = 21o
- a = x Let a = x to present the formula in it's most normal way
Solution
a^2 = 31^2 + 26^2 - 2 * 31 * 26 * cos(21) Find -2*31*26*cos(21)
a^2 = 961 + 676 -1504.93 Combine
a^2 = 1637 -1504.93 Combine again
a^2 = 132.07 Take the √ on both sides
√a^2 = √132.07
a = 11.5 Rounded.
Answer
x = 11.5